Borrelia genus, Epidemic relapsing fever and Endemic relapsing fever Flashcards
Borrelia genus general morphology
Spirochete, but have fewer coils.
Seven to twenty periplasmic flagella originate at each end and overlap at the center of the cell - twisting motility.
Borrelia recurrentis habitat - (Epidemic Relapsing Fever louse-borne)
Humans (no animal host)
Borrelia recurrentis Pathogenesis:
Vector- body louse
Crowded, unsanitary conditions (war, natural disasters)- increase the risk to be exposed to louse
Borrelia recurrentis clinical manifestation (epidemic relapsing fever)
Fever (can spread to blood causing bacteremia)
Periodic febrile and afebrile cycles where bacteria undergo antigenic variation
During afebrile period- specific IgM → complement-mediated lysis – bacteria disappear from the blood (hidden)
Borrelia can change their outer proteins by gene rearrangement- emerge as novel organism (change antigen, thus cause relapsing fever)
Endemic Relapsing Fever (tick-borne) - . Borrelia hermsii Habitat
zoonosis (e.g. rodents)
Borrelia hermsii (Endemic Relapsing Fever) Pathogenesis:
Vector- soft-shelled tick
Endemic relapsing fever clinical manifestation:
Fever (can spread to blood causing bacteremia)
1 week afebrile period (bacteria undergo antigenic variation), then febrile period (fever returns)
Endemic relapsing fever Diagnosis
Sample from blood (during fever)- using Giemsa staining
Antibody detection by indirect immunofluorescence assay
Cultivation- slow growth on artificial culture media (microaerophilic, complex nutrition requirement)
Cultivation does not used to be successful
Endemic relapsing fever Treatment
Tetracycline, Macrolides (Erythromycin)
Endemic relapsing fever Prevention
avoiding the vectors (wearing clothing that covers as much of the skin as possible and use tick repellents)
